And the pig, because it has a cloven hoof that is completely split, but will not regurgitate its cud; it is unclean for you. You shall not eat of their flesh, and you shall not touch their carcasses; they are unclean for you.

According to Jewish law, pork is one of a number of foods forbidden to Jews. These foods are known as "non-kosher" foods. In order for a meat to be kosher, it must first come from a kosher animal. A kosher animal must be a ruminant and have split hooves; therefore, cows, sheep, goats and deer are all kosher, whereas pigs (having only one sign of kashrut) are not kosher.[8]

During the persecutions of Antiochus IV Epiphanes, the Greeks forced the Jews to slaughter pigs in the Temple in Jerusalem, which did not improve the image of pork. There is, however, no aversion to the pig as an animal, that it is commonly cited as an example of what is not kosher is largely due to its prevalence.

Maimonides, the Jewish philosopher and legal codifier, who was also court physician to the Muslim sultan Saladin in the 12th century, understands the dietary laws chiefly as a means of keeping the body healthy. He argued that the meat of the forbidden animals, birds, and fish is unwholesome and indigestible. According to Maimonides, at first glance, this does not apply to pork, which does not appear to be harmful. Yet, Maimonides observes, the pig is a filthy animal and if swine were used for food, marketplaces and even houses would be dirtier than latrines.[9]

Rashi (the primary Jewish commentator on the Bible and Talmud) lists the prohibition of pig as a law whose reason is not known, and may therefore be derided by others as making no sense.[10]

The Chinuch Sefer HaChinuch[11] (an early work of Halachah) gives a general overview of the Jewish dietary laws. He writes 'And if there are any reasons for the dietary laws which are unknown to us or those knowledgeable in the health field, do not wonder about them, for the true Healer that warns us against them is smarter than us, and smarter than the doctors'.

The cultural materialistic anthropologist Marvin Harris thinks that the main reason for prohibiting consumption of pork was ecological-economical. Pigs require water and shady woods with seeds, but those conditions are scarce in Israel and the Middle East. Unlike many other forms of livestock, pigs are omnivorousscavengers, eating virtually anything they come across, including carrion and refuse. This was deemed unclean, hence a Middle Eastern society keeping large stocks of pigs would destroy their ecosystem. Harris points out how, while the Hebrews are also forbidden to eat camels and fish without scales, Arabnomads could not afford to starve in the desert while having camels around.[12] The taboo on eating pigs may also have been reinforced by similarities between pork and human flesh (which would have been evident in their shared physical nature and manner of decomposition, rather than requiring previous contact with cannibalism). Thus Juvenal finds the Jews reviling the eating of pig flesh as if it were cannibalism (Satire XIV). In the book God Is Not Great, Christopher Hitchens hypothesizes that the pork taboo arose from the similarity of pig flesh to the results of human sacrifice. (See God Is Not Great#Chapter Three: A Short Digression On The Pig; or, Why Heaven Hates Ham)

He has made unlawful for you that which dies of itself and blood and the flesh of swine and that on which the name of any other than God has been invoked. But he who is driven by necessity, being neither disobedient nor exceeding the limit, then surely, God is Most Forgiving, Merciful.

Scottish pork taboo was Donald Alexander Mackenzie's phrase for discussing an aversion to pork among Scots, particularly Highlanders, which he believed stemmed from an ancient taboo. Several writers who confirm that there was a prejudice against pork, or a superstitious attitude toward pigs, do not see it in terms of a taboo related to an ancient cult. Any prejudice is generally agreed to have disappeared by 1800.